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1986 740 GLE smog fail. High CO.

Didn't know about annual inspection. And I've had my smog license since '95.

I'd try looking at the signals from O2 , MAF, Temp and TPS at the back of ECU connector.
 
My 1990 940 Turbo failed smog a few times and I definitely recall getting a notice after just 1 year that it was smog time and it said Reason for Inspection: High Emitter Profile.

Another time I went to insure a 1986 744 I just bought from a tweeker and the insurance company had the VIN red flagged as a modified vehicle!

I tried to retire a car of mine thru the smog program and they denied me because registration had been late in the last 2 years!

Anyways thanks for the ideas. I'm gonna do some sensor readings as suggested. I haven't spent much time on this car but the temp tag is just about expired so I gotta get on it.
 
ZVOLV said:
My 1986 740 GLE has failed smog twice in a row for CO. Max is 1.5%. I failed at over 6%!!!!
Click to expand...

CO in monoxide, or are you referring to high CO2, which IS rich. CO points, IMO, to hi combustion temps, not richness, but a plug read is always good. I like vacuum gauges reads, too.

CA has lowered allowable emissions for older cars to well below, at times half of, that allowed when the cars were new!
 
I'm gonna post pics of the emissions results, but TODAY it failed for only high NOX at 15mph!!! HC and CO were very low!

I swapped the injectors as the only variable this time. I found one externally leaking and another started leaking when I pulled it from the manifold. Junkyard yellow tops were installed.

I lied. Last test was slight high HC ALSO. and off the charts Carbon Monoxide. 6 times over limit.

I changed the fuel injectors that were leaking at a minimum externally and now it's failing NOX! Even with a fresh kitty. It seems to be doing its job very well at 25 MPH, NOX is failing at 15mph.

Now NOX is about 1700 ppm at 15mph. Limit is about 700. FAIL!

NOX at 25 MPH was only 69ppm! PASS!

The tech scratched his head too and remarked it looks like I am lean now.
 
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whalepirot said:
CO points, IMO, to hi combustion temps, not richness
Click to expand...

This is bad intel

ZVOLV said:
I swapped the injectors as the only variable this time.
Click to expand...

Did you double check your mixture after this? Is the O2 sensor voltage switching like it should?

And idk what your ignition timing is set at, but retard it as much as the smog sticker allows. More advance = more nox

And is the thermostatic air cleaner working? Or is it sucking in hot air from the exhaust stove at all times? This is what usually kills MAF sensors, but hot air coming into the engine is doing you no favors. Hot intake air = higher combustion chamber temps = more nox

And plug your smog numbers into this guy: http://www.smogstats.com/lambda_cat.aspx

It'll help point you in the right direction
 
The car also has a high idle, seems like long cold crank, and now some stumbling/stalling on cold start has shown up.

I really need to post the numbers up. Sorry.

I never said CO2. That has to do with complete combustion. 13% is complete combustion. Besides, high combustion Temps create NOX. Not CO2. It's not one of the pollutants that is considered, but o2 and co2 are on the results anyways. It's just CO, HC, and NOX that count.

I have not confirmed oscillating voltage after injectors, but it's probably there. As far as the actual mixture I don't know. I would like an exhaust gas Analyzer but $$$. Even then, this is a loaded test on a dyno at 15mph and 25mph.

I also have started timing how long the car is tested at each speed. It was at 15mph for over 1 minute and 45 seconds! That's too long; I knew that part was a fail. 25mph was only about 35 seconds.

I may smoke test it for air leaks and clean the MAF at this point. Or its also for sale. Getting over it.
 
Smoke test revealed cracked accordion hose! I also found the charcoal cannister line fell off again from cracking even though I just re cut it.

Accordion hose and one more $50 smog check coming up!

I suspected air leaks due to the high idle. On these 2.2 cars airleak will make it go lean and idle faster. Lean at 15MPH but not at 25mph also made me feel like there may be an airleak. Those are the kinds of questions that are on the ASE L1 Advanced Engine Specialist test I am trying to pass by this summer to become a smog repair tech. Idle being lean but clears up at higher rpm van be indicative of an air leak.
 
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ZVOLV said:
Smoke test revealed cracked accordion hose! I also found the charcoal cannister line fell off again from cracking even though I just re cut it.

Idle being lean but clears up at higher rpm van be indicative of an air leak.
Click to expand...

:nod:

Nice find! That should help your nox numbers quite a bit. Remember to check dat mixture when it's all fixed up :cool:
 
Here is the pic

So I have an open thermostat in the air box and a torn intake hose. Do you think if I fix those it shall fix the NOX and I will pass..? The temp tag expired and I got pulled over and cited for expired registration on my way to work today!#@

2evf0qq.jpg
 
The certified smog repair tech I work with looked at the same charts above and he says crappy aftermarket cat. "Seen it all the time!"

He says the CO2 looks like perfect combustion and the O2 at 0.4% looks fine and NOT lean.

I asked the exhaust shop for a MagnaFlow cat since Walker cat was gonna take longer to show up he said, then I saw the parts guy show up with some no name brand.....I didn't call him out.

It's cheaper for me to install an air hose to fix the air leak and repair the thermostat airbox and try another smog check at this point, and also more convenient, to deal with that exhaust shop again. Exactly why I should have just done it myself.


So what say turbo bricks!?

Option 1: go MY route and fix air box and accordion hose small leak and re test?

OR

Option 2: Listen to my coworkers idea and go with a nice fresh quality cat and re test?
 
Mechanic 101...always do the more expensive stuff that requires more work and may or may not be an issue BEFORE you fix the obviously broken stuff that's quick and easy...
 
This guy is usually right.

I also may have damaged the cat driving it with the mixture being so rich for a while.

I'm gonna fix the air hose, fix the pre heat, make sure the coolant is topped off since there is a small leak, and I'm tempted to run premium fuel and dial the timing back to 10 degrees (min allowed) since right now it's at 12 degrees.

I have been trying to only change one variable at a time so I can measure the results in the name of science and learning, but right now it's costing too much $. I need this thing legal ASAP.
 
I passed!!!

2w3qpm1.jpg



Fixed torn accordion hose, fixed bad wiring and dead in tank pump, fixed thermostat in the air box, and fixed a coolant leak.

It was enough to get NOX below the limit. Still much higher than I want, but good enough to get my registration tags finally so I stop getting tickets. And I can sell the car now too legally in the next 90 days with this smog! It's worth about $1,000 more I hope.

The high idle is also gone now too. Smoke test for the win on that one.
 
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